The present invention relates to stereo image display units for stereo image display according to a stereo image signal provided by input means after image depth control.
Various stereo observation displays for displaying image for stereo observation have been proposed.
In a prior art stereo observation display, the depth position of display surfaces and the merging depth position are not coincident. Therefore, a state of inconsistency between the mergence of the observer""s eyeballs and the focus control may arise. When the inconsistency is increased, a human can no longer perceive a stereo image as a single image.
Several means for solving this problem have been proposed. Japanese Laid-Open Patent Publication No. 3-292093 discloses means for detecting an observer""s attention center using a glance motion detector and varying the parallax by moving lens according to depth information at the attention center. This controls xe2x80x9cdepth position of display surfacesxe2x80x9d such that the position coincides with merging depth position.
Japanese Laid-Open Patent Publication No. 7-167633 discloses means for detecting the observer""s attention center by using a glance motion detector and controlling the parallax such that the depth at the attention center is reproduced on display surfaces of a stereo image display or at a position spaced apart from the surfaces by a specified distance. This controls xe2x80x9cmerging depth positionxe2x80x9d such that this position coincides with the depth position of the display surfaces.
The above two prior art techniques are the same insofar as the observer""s attention center is detected and the depth position of stereo image is controlled on the basis of the depth information at the attention center. In these techniques, however, it is necessary to accurately detect the observer""s attention center. This means that a glance motion detector having high accuracy of detection is necessary, thus leading to high price of the unit. In addition, the glance motion detector adds weight. Therefore, where a head mounted display (hereinafter abbreviated as HMD) is used as a stereo image display, the glance motion detector causes the weight increase of the HMD.
Japanese Laid-Open Patent Publication No. 6-225197 discloses a monitor, which can automatically recognize objects in a monitored zone and automatically trace an object to be noted. In this monitor, however, the object to be noted is not automatically recognized for the purpose of the depth control of stereo image.
An object of the present invention is to provide a stereo image display, which can determine an observer""s high attention center point (or area) of an image without use of any special high detection accuracy glance motion detector and control the stereo image depth according to the depth information at the determined high attention center, thus providing a stereo image which is stable and can be very easily observed.
According to the present invention, there are provided the following featured stereo image display units;
Other objects and features will be clarified from the following description with reference to attached drawings.